There is a need for an improved apparatus for removing condensed water, oil, contaminants and other liquids from a compressed air system. It is desirable to allow a quantity of water to accumulate over time and then remove the collected water all at once. It is preferable to have a drain valve that operates automatically to periodically remove water from the compressed air system during normal operation thereof.
Known automatic methods to accomplish automatic water removal include: float traps, timed drain valves, demand type electronic drain valves, and flow drain valves utilizing a pneumatic pilot system.
Float trap designs typically take the direct approach of using the buoyant force of a float to directly lift a poppet valve from its seat to drain accumulated liquids. When the liquid level falls, the float falls and the valve closes. The major limitation of the float trap that is the valve seat area is limited by the buoyant force available to overcome internal pressure acting to hold the valve closed. Operation at higher pressure requires either a larger float or a smaller valve seat, in order that the buoyant force available is always greater than the force of internal pressure holding the valve poppet closed.
Similarly, magnetically coupled drain valves are known as disclosed, for example, in U.S. Pat. Nos. 2,893,427 and 5,080,126. These prior art devices suffer from the limitation of limited force available to keep the valve closed and the necessity of having two valve seats, each of which has to be sealed depending on the position of the valve. As such, it should be appreciated that there is a continuing need for a new and improved pneumatically piloted, float drain valve as set forth by the present invention which addresses the above-mentioned problems.